TL;DR - Posts on official Multnomah county blogs indicate that E Larch Mountain Road is closed at the ten mile gate for 2023, see: larch mountain road closed and multnomah county larch mountain, so this hike starts at the gate. Note that it requires a 1.6 mile traverse along the road before turning onto FS road 315 (which intersects with trail 441) for a 3.75 mile hike with about 1600 feet of up. The gate was open when I was went up and there was some traffic so the road hike is a bit sketchy; approach it cautiously. There is parking at the gate, no ATT cell service, and the off road hike is on a good trail through open old forest.
Long Version - The road up to Larch Mountain is gated at the ten mile milepost and is closed and un-plowed during the winter months. With that in mind, I originally planned a snowshoe from the gate last year. That didn't happen so when I heard (see above) that the gate was going to stay closed through 2023, I decided to do it as a summer hike. The drive up takes about forty-five minutes from SE Portland and there is a pull off for parking right before the gate (don't block access to the fire road!).
From the gate follow the road for about 1.6 miles; at this point, FS315 starts. It intersects with trail 441, which takes you to the parking lot below the summit observation point. I don't recommend the road hike if there is traffic. There's not much of a berm and a lot of blind curves. You might be able to hike through the forest on the left (north) side of the road but there are bands of brush, bogs, and gullies to negotiate. Staying on the road, the hike is rises roughly 1600 feet over 3.75 miles and, once off the paved road, meanders on a good trail through open beautiful, older forest. At the top, you'll encounter a picnic area and vault toilets; follow the old road up and you'll run into the path to the manmade observation platform, called Sherrod Point.
The observation platform is small, and on most days in the summer, crowded. With the road closed, it is a good bit quieter but still not a great place to set up an antenna or operate for an extended period. There is space to set up at the base of the platform on the southwest side but be careful: the area is small and the slope is steep. There wasn't any ATT cell signal, I did get APRS pings, and making four two meter contacts was quick and easy.
For a more strenuous hike that avoids Larch Mountain Road altogether, start at the base of trail 441 at Multnomah Falls, which is seven miles one way and climbs almost 4500 feet.